1. Field of the Invention
The invention relates to intelligent optical network techniques, and more particularly, to a method and an apparatus of routing convergence in the control plane of an intelligent optical network.
2. Background of the Invention
Along with the rapid development of communication techniques and sharp increase of data service transmission, the intelligent optical network has become a new important communication technique and been widely used due to its features such as dynamic allocation of network resources, transmission of high data volume and high performance-price ratio. In the intelligent optical network, link resources are crucial to a service establishment. The link resources in the intelligent optical network include link resources in the transport plane for bearing service data, and link resources in the control plane for transmitting service signaling messages.
In the intelligent optical network, the routing protocol is a very important intelligent protocol. In the routing protocol, the Internet Protocol (IP) serves as a network layer protocol and functions to flood the information of link resources in the transport plane, perceive the state of link resources in the control plane, and calculate a routing forward table in the control plane to provide a basis for forwarding signaling messages by the network layer.
In the related art, the routing protocol perceives the state change of link resources in the control plane, that is to say, routing convergence is implemented by a source node receiving a routing protocol message. For example, a link in the control plane is deemed as interrupted if the source node has not received a routing protocol message indicating that the service processing is normal within a period of time which is generally 40 s.
FIG. 1 is a simplified schematic diagram illustrating a topology structure of the control plane of an intelligent optical network. In FIG. 1, Node A 101 is connected to Node B 102 through optical fiber link 111 and optical fiber link 112, Node B 102 is connected to Node C 103 through optical fiber link 123 and Data Communication Network (DCN) or Ethernet switch 104, wherein, Node B 102 is connected to DCN or Ethernet switch 104 through Ethernet link 124, and Node C 103 is connected to DCN or Ethernet switch 104 through Ethernet link 132. It is specified in the routing table that the routing from Node A 101 to Node C 103 is through optical fiber link 111, Ethernet link 124 and Ethernet link 132 in turn. When there is a failure in optical fiber link 111, e.g., optical fiber break, the system initiates re-routing, and an established re-routing path is through optical fiber link 112, Ethernet link 124 and Ethernet link 132. However, if there is also a failure of optical fiber break in Ethernet link 124, the state change of the link may be not perceived within a long time due to a low speed of routing convergence, as a result, re-routing may not succeed within a long period of time.
As can be seen from the above technique scheme, since the convergence speed of the conventional routing convergence method is slow, system services will not be established within a long time or the re-routing fails when there is a service link failure in the control plane of the intelligent optical network, which further influences the survivability of network services.